• 11-11-2012
    PixieChik
    What are the advantages and disadvantages of carbon?
    Besides price?

    ETA: this is probably a stupid question, but does carbon crack in cold weather?
  • 11-11-2012
    Procter
    Advantages: higher strength to weight ratio than steel or aluminum. (tensile and shear strength specifically, but, not the third, compression, see below)

    Manufacturing process allows for very customized, purpose built parts that meet exact design characteristics, i.e. custom shaped frame tubes with exact dialed in strength in different directions of force, and continuous joints . . . Compare with al/steel where designers may struggle with shapes that are hard to extrude or weld with the same strength

    Good elasticity & shock absorption, which is also 'tunable' based on construction

    As for brittleness at low temps, I'm not sure whether aluminum or carbon wins, but neither will have a problem at normal temps for biking (i.e down to zero degrees F)

    Edited: Higher fatigue strength (error corrected) :P

    Disadvantages:

    Price

    Does not fail as predictably (snaps instead of bending)

    I think it also has slightly lower compression strength, putting limitations on its use, for example requiring that you don't clamp it too tight in handlebars and posts.
  • 11-11-2012
    swan3609
    Advantage: Damn those are some sexy Carbon curves and weaves
  • 11-12-2012
    trailbrain
    Quote:

    Originally Posted by ddprocter View Post
    Lower fatigue strength: thousands of cycles of weight/unweight, small/med hits and forces on any material will eventually cause it to fail . . . Carbon fails just a little quicker than AL keeping all other variables constant, for same number of weight cycles.

    Really? Doesn't look like Santa Cruz has an issue with that.

    Pinkbike Visits The Santa Cruz Test Lab Video - Pinkbike
  • 11-12-2012
    Joules
    Quote:

    Originally Posted by trailbrain View Post
    Really? Doesn't look like Santa Cruz has an issue with that.

    Pinkbike Visits The Santa Cruz Test Lab Video - Pinkbike



    yeah, that statement (carbon having a short fatigue life) is about 180 degrees from reality. Carbon has a nearly infinite fatigue life; aluminum, pretty short as far as metals go - which is why you don't see aluminum coils on springs.
  • 11-12-2012
    Procter
    Whoops you guys are right about fatigue, I remembered that wrong.
  • 11-30-2012
    Jaybo
    carbon frames get mucked up and show wounds like crazy.
  • 11-30-2012
    mik_git
    I think that traditionally carbon fibre was used to make stuff that was very light and very strong for a small operational window. Take it outside what it was designed to do and and bad things could happen.
    These days I think that, well especially for FS bikes or non pure XC bikes, they make them strong and light, but nowhere near as light as they could make them, its more that they can make whatever shape they want without the restrictions of tubing and laying up carbon for strength over lightness (still a hefty does of lightness but thats not the priority).
    Its when you are chasing maximum strength/weight that issue appear, look at the front wing of an F1 car, tiny little struts of CF holding on the wing, transferring 100's and 100's of kg of load to the chassis. No problem, but as soon as you give it tap in the wrong direction, the wing falls off.

    I remember an article in bicycling magazine back in 91-92, they were interviewing people from different material manufactures for mtb's and the guy from kestrel said that the main reason they had bikes back from failures was people crushing them in car racks
  • 12-01-2012
    Varaxis
    Advantage: higher potential quality of bike frame, and other large objects/components.

    Disadvantage: lower potential quality of products, especially smaller objects. Extremely difficult, if not virtually impossible, to judge or predict its nature (high quality or mediocre or low quality) from its outside appearance.

    There's well designed and high quality carbon and there's poorly designed carbon and then there's mediocre carbon. Take away the fancy outside finish and decals, and you wouldn't be able to tell which is better for sure. A brand can market a mediocre carbon bike and make it seem amazing. A brand can make their downtubes super thick and allow some journos to swing [a 6 lb frame, without a good handle on it] into a concrete block and make you think all their carbon design are like that. A brand can smack their carbon product with a light ball peen hammer, suspending the product in a loose flexible manner, and... lots of dramatizations out there; even this post is one.

    You can't generalize that carbon is stiffer than alum or steel. Hell, you can't even generalize that alum is stiffer than steel, though there are people that believe in both. Small carbon parts are especially prone to flex. Carbon is typically only very stiff along 1 axis, while metal is equally stuff in all directions. Things like carbon RD cages are probably not that stiff laterally. Heck, some carbon crowns and steerer units* and even many carbon cranks (and carbon stems) don't match alum in overall stiffness, even considering their weight.

    It's one of those things you almost *must* try before you buy. Or rely on expert opinions. Or just blindly trust brands, that may suit your style. You might find Trek makes their high end carbon bikes for medium sized athletic types, which might not feel so great under clydes looking for a bike that helps them up the hill on their XC trails faster/easier. You might find Santa Cruz tests their bikes to adequately hold up to clydes (they even have a test called "Big Fat Ass")... You might find another brand makes things that fit women well... you can choose brands based on that, but not based on hype and most forms of marketing.

    Don't expect bargain priced carbon to be hitting the highest potential. Some call it black magic. It's probably wisest to go with carbon made by those who have put the most research into it, though with the Taiwanese being experts at it and able to make frames for others... without knowing how they're made or seeing comparative lab test results, it's not really feasible to tell which are better, other than through actual ride testing (and long term testing, especially if warranties are not generous).

    It's really hard to sum up. If you want to know more, you basically have to research the raw materials, such as the carbon fiber (and its specific properties, such as modulus, tensile strength, etc.) and what form it arrives in (TOW, pre-preg, etc.) the resin, what other materials they mix in, the process at which they cut and lay-it up, compress, mold it, cure it, etc. Whether it's lugged, tube-to-tube, monocoque... there's more to it, and I'm no expert by any means, so I'm not going to try and make myself sound like one by going in-depth.
  • 12-02-2012
    chksix
    I'd have thought that the airline industry had ways of telling bad carbon vs good. Ultrasound or x-ray could do it.
  • 12-02-2012
    PixieChik
    Thanks for the replies. I decided I am so far from being an elite rider that the extra expense of carbon isn't worth it for me.

    Went with an ASR-5 Enduro build. I absolutely LOVE this bike. It's crazy fun to ride!